Train control



A Jan. 5, 1937. NQ c.-L. BROWN 'TRAIN CONTROL Filed Apri?. 15. 1922 EmiL M\ .We nu@ afl . viding Patented Jan. 5, 19.37

umriss stars GFICE General Railway Signal Company, Gates, N. Y., acorporation of New York `Application Aprill 15, 1922, Serial No. 553,032

4.0 Claims.

` invention relates to automatic train control systems ofV theintermittent type, and particularly to means for transmitting controlinuences from the trackway to a moving vehicle.

In automatic train control systems, it is desirable to transmit controlinfluences from the trackway to moving vehicles in accordance withtrallic conditions in advance. Such. control inluences are preferablytransmitted inductively through an intervening air gap, without physicalcontact betweenv car-carried and trackway devices..

`One important principle to be observed in construction of safetydevices for railroads, is that of the failure on the side of safety.Following out: this principlein an inductive type of train controlsystem, it is expedient to utilize the inlierentrmagnetic properties ofa body oi iron along the trackway to produce a stopping or dangerinfluence, so that if wires break, batteries 'become exhausted', orother similar failures occur, the safety o the system will not bedestroyed by; .such failures, but the trainwill be stopped thereby. Inutilizing thev inherent properties of? iron in trackway devicesoi thiskind, suitable vmeans mustl be provided forV removing or counteractingthe effect of such devices under clear trac conditions. On the otherhand, it is sometimes desirable to provide communicating devicespreferably also of the inductive type for transmitting a clearinginfluence to remove a restriction which has been imposed by such dangeror stopping influe-nce. Clearing influences should be transmitted bydevices operating on the open-circuit principle, that is, by deviceswhich are constructed so that those portions thereof which are likely tofail, such as a circuit wire and the like, if a failure occurs, willprevent the transmission of a clearing influence. In other words, dangerinfluences should be transmitted by devices along the trackway whichhave inherent properties which can not fail, the eiect of which may beremoved or counteracted by a less reliable device in accordance withtrafc conditions; whereas clearing influences should have their'presence dependent on the less reliable-or weaker links of a chain ofthe necessary elements. ,i

The present invention is directed toward procommunicatingV apparatuswhich will transmit suchl danger control iniiuences4 inductively from a`dead orinert trackway device, that is, one which requires no energy ineither itsY active or inactive conditon,. and in which an iniiuence maybe transmitted to. suitable vehiclethe carried apparatus, if the vehiclemoves by such trackway devices, or if it stands over such deviceswithout any relative movement with respect thereto; and is furtherdirected toward the provision of devices constructed on the normallyopen or deenergized circuit principle for transmitting clearinginuences., these devices likewise being effective with very little or norelative motion between car-carried and track- Way devices.

Other objects and purposes of the invention will appear as thedescription progresses.

In describing the invention -in detail, reference will be made to theaccompanying drawing, in whichr- Figure l shows diagrammatically thetrackway of a railway block signal system upon which the trackwayapparatus of one embodiment of the present invention has beensuperimposed;

Fig. 2 shows diagrammatically one form of carcarried apparatus embodyingthis invention, the parts and circuits being shown more with a View ofmaking it easy to understand the invention and its mode of operation,than with the purpose of illustrating the parts preferably employed inpractice; and

Fig. 3 is an enlarged side view of the danger control or knock-down carelement.

The danger impulse transmitting means embodying the present invention,comprises in general a track element T, located at desired controlpoints along the track and suitably controlled in accordance withtrafiic conditions; and a knockdown car element KD and associated partscooperating with `said track element T so as to cause interruption of acircuit on the car, or in any other suitable way produce an action onthe car Vunder dangerous traine conditions which can be utilized in anyof the well-known Ways to regulate the movement oiV trains. Theresetting or clearing devices generally comprise a carcarried primarytransformer-portion CP supported on a vehicle for communication with atrackway secondary transformer-portion TS, and a trackwaytransformer-portion TP adapted to communicate at the same time with acar-carried secondary transformer-portion CS, said two trackwaytransformer-portions being connected in a closed circuit under cleartraffic conditions.

Various arrangements of trackway circuits for controlling the conditionof the track element T and the transformer-portions TS and` 'I'P may beemployed, and in the accompanying drawing there is shownY only onetypical arrangement. Referring to Fig. l, the track rails l are dividedby insulated joints 2 into blocks in the usual way, one block I and theadjacent ends of two other blocks H and J being shown. Since the partsassociated with the various blocks are the same, they will be given likereference characters with distinctive exponents. Each of the blocks isprovided with a track battery 3 and a track relay 4, in the same way asin ordinary block signal systems. A train control system embodying thepresent invention may be used with, or without, the usual fixed signals;and I have illustrated such fixed signals X conventionally, withoutattempting to illustrate their Well-known control circuits.

The track element T in the specific form. illustrated, comprises aU-shaped yoke or core 5, preferably of a good quality of laminated ironterminating in enlarged pole pieces 6, and which is provided with a coill. This track element T is located at the appropriate control point ator near the entrance of each block, and in the particular embodimentillustrated has been shown a short distance in the rear of the insulatedjoints 2. These track elements are preferably disposed lengthwise of thetrack and on the outside of the rails, so that the pole pieces 6 aredisposed a short distance above the surface of the rails. The coil 'I ofthe track element T is adapted to be closed in a circuit of lowresistance by the front contact of a line relay 8. This circuit may betraced as followsz-beginning at the coil l, wire 9, front contact I ofthe line relay 8, wire II back to the coil 'l of the track element T.

The trackway transformer-portions TS and TP similarly comprise aU-shaped yoke or core I2 terminating in elongated pole pieces I3, andare provided with coils I4 and I5, respectively. These coils undernormal or clear traic conditions, as illustrated, are connected inseries in a closed circuit, which may be traced as followsz-beginning atthe coil I4, wire I8, coil I5, wire i9, front contact I6 of the linerelay 8, wire I'I back to the coil I4 of the transformer portion TS.

The line relay 8 is energized when the block at the entrance to which itis placed and also the next block in advance are clear, through acircuit which may be traced as followsz-beginning at the terminal B of abattery, wire 201, front contact 2|1 of the track relay 41, wire 22,front Contact 23 of the track relay 4, wire 24, Winding of the linerelay 8, wire 25 to the common return wire C, which is connected to theopposite terminal of the battery. By looking at Fig. 1, it is readilyapparent to those skilled in the art that the line relay 8 will only bedeenergized when either of the blocks I or J or both are occupied, orare in danger condition, thus putting the track element T and thetransformer-portions TS and TP in their active: condition under bothcaution and danger traffic conditions of the block I.

In describing the car-carried apparatus illustrated in Fig. 2, theseveral devices will rst be separately described, after which the mannerin which they are connected and the operation of the car-carriedapparatus will be described. The car-carried knock-down element KDheretofore mentioned, comprises a U-shaped yoke or core 25 terminatingin elongated pole pieces 2l and 28, this core being constructed oflaminated transformer iron, thus increasing the efficiency of the carelement by decreasing the flow of eddy currents and their detrimentaleffects. One of the legs 29 formed by the U-shaped core 2G is providedwith a primary coil P, and the other leg 3B is provided with a secondarycoil S.

The U-shaped core 26 is provided with a projection 3l extending parallelto the leg 29 and closely adjacent thereto, so that a shunt magneticcircuit is formed through the leg 29, pole piece 21, projection 3|, core26 back to the leg 29. This projection 3| is provided with a maintainingcoil 32, which is connected in series with the secondary coil S, in amanner so that the voltages induced in these tWo coils due to leakage ofux caused by the primary coil P through the two multiple magnetic pathsincluding said coils, will be opposite or subtractive. This knock-downelement KD is preferably mounted on a railway vehicle so that it willhave a denite relation with respect to the track rails and trackelements, regardless of movement due to the jars and vibrationsordinarily encountered. This is preferably accomplished by mounting saidelement in a casing to protect it from the weather, this casing beingpreferably made of non-magnetic material so as not to affect itsoperation. This casing is preferably mounted from the side frame of arailway truck by a suitable initially tensioned spring device, so thatordinary jars and vibrations will not permit relative movement betweentheelement and truck, but that such relative movement is possible whensevere shocks and jars occur.

The car-carried transformer portions CP and CS each comprise a U-shapedcore 33, preferably constructed of laminated iron terminating inenlarged pole pieces 34. The transformer-portion CP is provided withexciting coils 35, and the transformer-portion CS is provided withsecondary coils 36. These transformer-portions are supported from thevehicle in a manner similar to that of the knock-down element KD justdescribed.

The car-carried apparatus also includes a control relay CR. This controlrelay CR may take any one of various forms, but preferably comprises analternating current electro-responsive device of the two-element type,so that a large amount of energy for actuating this device may bederived directly from a source of alternating current. The moving partsof the relay CR are preferably light and well balanced, so that it will.be quick acting and not affected by jars and vibrations. This relay hasbeen conventionally illustrated, and comprises a local phase Winding 31and a secondary phase Winding 38 operating a contact 39 against thetension of a spring 40.

A similar relay for responding to clearing or pick-up control influencesis provided. This relay has been designated PR, and comprises a localphase winding 4I, a secondary winding 42, and a movable Contact 43normally biased from a stationary contact 44 by a spring 45. Theserelays CR and PR, are preferably supported in a heavy casing which isspring supported from the body of the railway vehicle, to protect themfrom jars, vibrations, and the like.

A suitable alternating current generator AC is provided for energizingthe primary coil P, the coils 35 of the transformer-portion CP, and thelocal phases of the relays CR and PR. This generator AC is constructedand operated to produce an alternating current of the desired frequency.This frequency is preferably reasonably high for reasons which willappear hereinafter.

Since the impulse transmitting means embodying the present invention maybe used to control any suitable type of brake or train controlapparatus, and since the particular form `of this apparatus forms nopart, in itself, of the present inventiomll have illustratedconventionally a device K, in the form of an electro-pneumatic valvewhich may be used to' vent the train pipe and apply the brakes directly,or govern the operationv of any other form of speed regulating orbrake-controlling mechanism. This device K is normally energized,` andis set into operation when deenergized. While the device K may be madeso as to be directly operated by the control relay CR, or may beoperated by .an intervening repeater relay, for convenience no suchintervening repeater relay has been disclosed. A

. Under normal conditions, that is, with a train equipped with theapparatus illustrated in Fig. 2 moving between control points along atrack under clear traffic conditions, theprimary coil P will beenergized by alternating current from the generator AC, through acircuit which may be traced as follows2--beginning atV the generator AC,wire 46, primary coil P, wire 41 back to the alternating currentgenerator AC. The now of alternating current through the primary coil Pproduces a comparatively high .alternating magnetornotive-force in theleg 29 of the knock-down car element KD. The coil P is preferablydesigned ,with reference to the magnetic circuit of the knock-downelement KD, so that the flux leaking through the air-gap between thepole piece 21 and the projection 3l, and other paths in multipletherewith, will set up sufficient counter E. M. F. in the coil P toreduce the current owing therein to anV amount necessary to produce saidilux without undue heating of this coil. In other words, the currentflowing is that necessary to produce a certain alternating flux plusthat necessary to overcome the iron and copper losses, that is, it isthe exciting current.

The magnetic circuits of the knock-down element KD are so designed thatra large percentage of the flux will leak through the projection 3| andmaintaining coil 32, thereby inducing a voltage in this maintaining coil32. A small amount of flux will also leak from one to the other of thepole pieces 21 and 2B through the secondary coil -S back through theback yoke of the core 26` to the leg 29. This alternating leakingv uxwill induce a small voltage in the coil S which is in opposition to thevoltage induced in the maintaining coil 32, this voltage, however, beingso small as compared with the voltage induced in the maintaining coil,that the voltage induced in the maintainingY coil predominatesthereover, thus causing a current to flow in the circuit through `thesecondary phase Winding 38 in the direction `52, local phase winding 31of the control relay CR, wire 53, front contact 54 of the control relayCR, wires 55 and 56 back to the alternating current generator AC.

With the two windings of the control relay CR energized in the manner asjust described, the front contact 39 will be maintained in its closedposition, as illustrated, against the tension of the spring 40. Thephase relation between the curl rents in the local phase winding 31, andsecondary energized by alternating current from the genert;

ator AC flowing through a circuit, which may be traced asfollo-wsr-beginning at the generator AC, wires 5l, 51 .and 58, windingof the device K, wire 59, movable contact 39 of the control relay CR,Wire 55 and` 5B back to the alternating current generator AC. With thedevice K energized the train may proceed without ,any restriction.

The restoring or pick-up relay PR is connected so that it will beenergized when alternating current is induced in the secondary coils onthe carcarried secondary transformer-portion CS, and controls a circuitwhich bridges the contacts included in the stick circuit of the controlrelay CR. The circuit for energizing the local phase winding of thepick-up relay PR may be traced as followsz--beginning at the generatorAC, wires 5I, 51 and 60, local phase winding 4l of the pick-up relay PR,wires 5l, 52 and 56 back to the generator AC, 'Ihe secondary phasewinding of the pick-up relay PR receives its energy through the il'transformer portions CP and CS mounted on the railway vehicle, and thecooperating transformer portions TP and TS located along the trackway,as heretofore described, the Vprimary transformer-.portion CP beingenergized by a circuit which may be traced as followsi-beginning at thegenerator AC, wire 65, coil 35 or?V the primary transformer-portion CP,wire 55, the other coil 35 of said transformer-portion, and wire 66 back.to the generator AC.

The energizing circuit for the secondary'phase winding of the pick-uprelay PR may be traced as followsz-beginning at th-e coil 36 oi thetransformer-portion CS, wire 5S, coil 35, wire 58, secondary phasewinding t2 of the pick-up relay PR, wire 10 back to said coil 35.

Referring particularly to Fig. 2, let us assume that a railway vehicleequipped with this apparatus in its normal condition is moving along thetrackway so that the knock-down element KD passes over a track elementT, having its winding 1 open-circuited, because the block at theentrance to which it is placed, or the next block in advance thereof, isoccupied and the line relay 8 is deenergized. During the period Vof timethat the pole pieces 21 and 28 of the knock-down element KD are-directly over the pole pieces (i of the track element, the reluctancethrough the U-shaped core 26 will be much reduced due to the presence ofthe track element T. This reduction of the reluctance through themagnetic circuit just mentio-ned causes .an increase of alternating iluxthrough the secondary coil S, and at the same time causes a reduction ofthe alternating flux through the projection 3|. This reduction of thealternating magnetic flux through the projection 3i is accounted for bythe fact that the total flux through the coil P is not changedmaterially, because this alternating flux Yis that which is necessary toproduce the necescurrent flowing therein. Or in other words, thealternating flux is dependent on the voltage impressed on the primarycoil P and is practically independent of the reluctance of the magneticcircuit through this coil, that is, when the reluctance through theelement KD is reduced the magneto-motive-force induced in the primarycoil P is correspondingly reduced which, of course, will reduce theleakage flux through the projection 3i.

Since, now, the alternating iiux passing through the secondary coil Shas been materially increased, and the alternating flux passing throughthe maintaining coil 32 has been materially reduced, the current flowingdue to the two opposing voltages induced in these coils may have beenreduced substantially to zero, or may even have been reversed, dependentupon which of these two voltages predominates. In any event, the severalparts are so designed that when the element KD passes over a trackelement T when in its eifective condition, the torque of the controlrelay CR will be either much reduced or will be reversed. The momentarydeenergization of the control relay CR allows the front contact 39 to bebroken, thereby opening the circuit through the local phase winding 31of the control relay CR, thereby deenergizing it entirely andpermanently, this being a stick circuit. Further, the dropping of thefront contact 39 also interrupts the circuit through the device K whichinterruption will cause K to be actuated to control the train in amanner dependent upon the device K and the apparatus controlled thereby.

The train may now proceed through the block restricted by the traincontrol device K. Let us assume that during the time the train passesthrough the block at a restricted speed that the two blocks next inadvance thereof have become clear. This will, of course, cause the linerelay 3 at the entrance of the next block in advance to be maintainedenergized, thereby coupling the coils of the two trackwaytransformer-portions TS and TP together through the circuit heretoforetraced. During the time the car-carried transformer-portions CP and CSare in communicating relationship with the trackwaytransformer-'portions TS and TP, respectively, a chain of energytransmitting and transformer devices is completed, whereby the secondaryphase winding t2 of the pick-up relay PR is energized by alternatingcurrent from the generator AC. This chain of devices comprises atransformer consisting of the transformer portions CP and TS havingtheir magnetic circuit completed through air gaps, and this transformerener-gizes another transformer consisting of transformer-portions TP andCS having a similar magnetic circuit, this transformer being connectedto the secondary phase Winding 42 of the pick-up relay PR. Consequentlywhen, and only when, this chain of devices is completed, energy will besupplied to the secondary phase winding 42 of the pick-up relay PR; andsince the local phase winding thereof is continuously energized, therelay will be actuated closing its contact and completing a pick-upcircuit. Obviously, this is only possible when the line relay isenergized, which is only true when the adjacent block and the next blockin advance are clear.

This pick-up circuit may be traced as follows: beginning at thegenerator AC, wires 5l and 52, winding 31 of the control relay CR, wires53 and 1l, front contact 43 of the pick-up relay sary counter E. M. F.in the coil P to limit the PR, wires 44, 62 and 56 back to the generatorAC. The completion of this circuit will energize the control relay CRmomentarily, thereby completing its stick circuit heretofore traced.This Vwill permanently energize the control relay CR which in turn willenergize the train control device K, thereby removing the restrictionenforced by this device, which only depends on its design andconstruction as heretofore explained. In any event, the train may nowagain proceed unrestricted by the train control device K.

Assuming now that a railway vehicle passing along the trackway with thecar apparatus in its normal condition in the same manner as heretoforedescribed is passing over a track element T when in its clear traifccondition, that is, with its coil l closed in a circuit of lowresistance through the front contact Ill of the line relay 8. During thetime that the knock-down element KD has its pole pieces 21 and 28 overthe pole pieces 6 of the track element T, a small amount of ux will leakthrough the U-shaped core of the element KD and the core 5 of the trackelement T. This small amount of alternating flux will cause a relativelylarge alternating current to be set up in the winding 1, therebyproducing an opposing alternating magneto-motive-force which willprevent a stronger iield of flux from passing through this magneticcircuit. The slight amount of additional alternating flux passingthrough the secondary coil S will increase the voltage induced in thiscoil slightly, thereby reducing the current flowing in the secondaryphase winding 38 to a certain extent. This slight decrease of currentwill, however, be insufcient to cause the control relay CR to beactuated, therefore not aifecting the operation of the train controldevice.

Car-carried apparatus of an inductive influence transmitting means has,therefore, been provided which will transmit a danger or knockdowninuence when passing over a track element comprising an inert mass ofiron, but which will not transmit an influence if such a mass of iron ispassed over when provided with a coil closed in a circuit of lowresistance, the functioning of this means being dependent upon analternating flux, therefore enabling it to function when the device isin communication with a track element in its effective or open-circuitcondition continuously, that is, when standing over it, as well as whenit passes thereby at a comparatively high rate of speed. Further, theapparatus embodying this invention includes devices for restoring orpicking up the devices actuated by such a knock-down influence whentraflic conditions again clear up, the restoring device likewisefunctioning through an air gap without any physical contact between thetrackway and car-carried devices; and employing alternating current sothat the device will function, regardless of whether the car-carried andtrackway devices are in constant communication, or whether they arepassing by each other at a commercial train speed, providing the traflicconditions are such that a pick-up influence should be transmitted.

It should also be noted that the car-carried apparatus for transmittingknock-down influences is constructed entirely on the closed energizedcircuit principle, for instance, if the circuit through either of thephase windings of the controy relay CR is interrupted, the device K willbe actuated, thereby enforcing a restricted speed in a manner dependentupon this device. If the exciting circuit Vof the primary coil P shouldbe interrupted, no current would be induced in the secondary phasewinding 38 of the control relay CR, thereby actuating the device K in asimilar manner; and likewise if the alternating current source shouldentirely fail, or only the circuit for energizing the train controldevice K should fail, this device would be actuated to enforce arestriction dependent on said device. Likewise, if the circuit`including the coil of the track element T should not be intact for anyreason, a knock-down influence will be transmitted, because the inherentproperties of the iron core of this element can not fail. On the otherhand, that portion of the automatic train control apparatus which isnecessary to restore the train control device K is, as it should be,entirely designed and constructed on the open-circuit principle, so thata failure of any one of the circuits included in this apparatus willprevent the transmission of a restoring infiuence, thereby making itimpossible to transmit a false restoring or proceed influence due tofailure. This is readily apparent by noting that Veach portion or linkof the chain of devices heretofore mentioned is necessary to transmit arestoring or proceed inuence, and consequently if any one of them shouldfail, no such influence can be transmitted.

A relatively high frequency is preferably employed in order that o-ne,or more, cycles may transpire during the time the car-carried andtrackway devices are in communication during the passage of a train athigh speed, this being desirable because the control relay shouldrespond to such communication under danger trafc conditions, and at thesame time should not be actuated when the alternating current whichmaintains'it energized passes through zero. Another advantage inemploying such a frequency, resides in the fact that the magneticproperties of the track element T, as compared with such properties ofcrossing rails, increase with the frequency used. This, it is believed,is due to the quality of the iron used and its laminated structure. Theemployment of such relatively high frequency, therefore, it is believed,improves the operating characteristics of the apparatus itself, and alsoincreases the marginal effect the track element produces over that of acrossing rail.

It should be noted that lthe apparatus employed for the transmission ofknock-down influences has been mounted on the righthand side of thetrack, considering trailic in the direction of the arrow, and that thedevices for transmitting pick-up or proceed influences have been mountedon the lefthand side of the trackway. This has been done so that thecar-carried devices provided for one purpose can not get intocommunication with the trackway devices provided for the other purpose.Further, duplicate equipment may be provided on the vehicle so thateither end of the vehicle may run ahead, automatic means being providedto cut in the proper set of devices, the operation of said automaticmeans being dependent on the direction of movement of the train. Thismay be accomplished by an obvious adaptation of the means described inthe co-pending application No. 544,561, led March 17, 1922, by CharlesS. Bushnell.

While I have described only one specific embodiment of the invention, Idesire to have it understood that the particular construction shown anddescribed may be modified and adapted to meet the various demands forcommunieating devices in automatic train control systems withoutdeparting from the spirit and scope of the present invention. f

What I claim as new and desire to secure by Letters Patent, is:-

l. Influence communicating means for automatic train control systemscomprising, a car element having two partial magnetic circuits, meansfor producing a substantially constant alternating flux in said element,and trackway means including adjustable electrical means for at timesshifting flux from one to the other of said partial magnetic circuits.

2. A car element for receiving inductive inuences from the trackwaycomprising, a threelegged yoke of magnetic material, means for producingan alternating magnetto-motive-force in one of said legs, and means fordetecting the respective amounts of flux in the other two legs.

3. A car element comprising, a yoke having two partial magneticcircuits, means for producing an alternating magneto-motive-force insaid circuits, and a Winding magnetically associated lwith each of saidpartial magnetic circuits, said windings being connected in series sothat the voltages induced by said magneto-motive-forces will be in phaseopposition.

4. In an automatic train control system, the combination of means fortransmitting danger control influences comprising, car-carried devicesand circuits in which each circuit is energized by alternating currentand adapted to be actuated by trackway devices each comprising q a barof iron when in its active condition and means for controlling each toan inactive condition; and means for transmitting restoring influencescomprising, car-carried and trackway transformer-portions which areenergized from a source Vof alternating current on the vehicle and whichact under clear tramo conditions to transmit a restoring inuence.

5. Inductively acting inuence communicating means for automatic traincontrol systems comprising, a receiving element on a car including threemagnetically coupled coils, a source of alternating current on the carenergizing one of said coils, an electro-responsive control deviceconnected with the other two coils in series and normally energized bycurrent induced therein from the energized coil, one of said two othercoils being only weakly excited and opposing the excitation of the othercoil, and a track element including a magnetic core for at timesincreasing the excitation of the weakly excited coil, thereby opposingthe excitation of the strongly excited coil and producing a reduction inthe energizing current normally supplied to said control device.

6. In a train control system, the combination with a car-carried sourceof alternating current, automatic means partly on the vehicle and partlyon the track deriving its energy wholly from said source forcommunicating two distinctive initiating and restoring controlinfluences through an intervening air gap at predetermined controlpoints along the track, said means including two separate tramocontrolled circuits on the trackway for respectively determining thecommunication of said influences, one circuit if open causing thetransmission of the initiating influence and the other circuit if closedcausing the transmission of the restoring inuence, and automatic brakecontrol apparatus initiated and restored by said inuences.

7. In a train control system, the combination with safety apparatus on avehicle adapted when initiated to continue to be effective untilrestored, of means initiating the operation of said safety apparatusdependent on traffic conditions and including a track deviceconstituting an inert magnetic body when in its active stoppingcondition, means for restoring said apparatus comprising, a source ofalternating current on the vehicle, a trackway circuit, and cooperatingcarcarried and trackway devices energized from said source and eifectiveat predetermined control points only if said circuit is closed.

8. Car-carried means adapted to be influenced by a cooperating trackelement constituting a magnetic body and comprising, a source ofalternating flux, two partial magnetic circuits supplied from saidsource, and electro-responsive means operable upon a predeterminedchange in the relative reluctance of said magnetic circuits and meansincluding adjustable electrical means to change said relativereluctance.

9. In a train control system, the combination with a track deviceconstituting an inert magnetic body when in the active stoppingcondition, car apparatus cooperating with the track device andcomprising, a magnetic core, a primary coil on the core constantlyenergized by alternating current, a secondary coil on the core energizedfrom the primary coil by transformer action, a third coil magneticallyassociated with the primary coil and included in a path normally ofhigher magnetic reluctance than that through the secondary coil, andelectro-responsive means connected with the secondary and the thirdcoils in series, the track device acting to decrease the reluctance ofthe magnetic circuit through the secondary coil but not the third coil.

10. A car element for train control systems comprising, a source ofalternating current, two partial magnetic circuits of normally differentreluctance both energized from said source, and two oppositely woundcoils connected in series and contained one on each of said magneticcircuits.

11. In a train control system, the combination with a track elementhaving a U-shaped magnetic core and a winding thereon, trackV circuitcontrolled means for placing said winding in a closed deenergizedcircuit of low resistance under clear traffic conditions and on opencircuit under dangerous traic conditions, a car element having amagnetic core arranged to come in superimposed relation with the core ofsaid track element, a source of periodically fluctuating current on thecar, an exciting coil on said car-carried core energized from saidsource, a secondary coil on said car-carried core in which voltage isinduced as that core comes over the core of the track element with itswinding on open circuit, and electro-responsive means normally energizedfrom said source and having its energizing current reduced by thevoltage induced in said secondary coil.

12. In a train control system, the combination with a source ofalternating current on a vehicle, of separate initiating and restoringreceiving devices on the car moving in diierent paths along the trackand both energized wholly from said source, and track circuit controlledtrackWay devices separately cooperating with said receiving devices andeffective to produce thereby initiating and restoring influences,respectively, independently of the speed of the car.

13. In a train control system, car-carried brake control apparatusadapted when set into operation to continue to be effective untilrestored, a source of alternating current on the car, means including atrack device constituting an inert body of iron when in the activestopping condition for at times under dangerous traffic conditionssetting said brake control apparatus into operation, a normallydeenergized circuit adapted when energized to restore said apparatus,and two pairs of cooperating car-carried and wayside elements effectiveonly if a trackway control circuit is closed for energizing the circuiton the car by transformed energy derived from said source.

14. In a train control system, the combination with a source of currenton a vehicle, separate initiating and restoring receiving devices on thevehicle moving in different paths along the track, and trafliccontrolled track devices separately iniiuencing said receiving devices,said receiving devices and track devices deriving their energy whollyfrom the source on the vehicle and having their effective actiondependent upon a series of normally energized circuits and a series ofnormally deenergized circuits, respectively.

15. In an inductive impulse communicating means for train controlsystems, the combination of a car element having a coil normallyenergized by alternating current, electro-responsive means on the carnormally maintained inactive by the flow of alternating current in saidcoil of the car element, said car element having another coil adapted tohave voltage induced therein at times by ux derived from the normallyenergized coil, the voltage induced in said another coil causingdeenergization of said electro-responsive means, and a track elementcooperating with the car element and causing such induction of voltagein said another coil to actuate the electro-responsive means, thefrequency of said alternating current being high enough to allow one ormore cycles to take place during the period of effective cooperation ofthe car and track elements at the highest speed of the car.

16. A car element for automatic train control systems comprising, a yokeof magnetic material of a conguration resulting in two partial magneticcircuits one of which has a lower reluctance than the other, means forcontinuously supplying undulating ux to said circuits, and trackwaymeans having means for varying the electrical characteristics of thetrackway means.

17. Inductively acting influence communicating means for automatic traincontrol systems comprising, a receiving element on a car includingmagnetically coupled conductors, a source of alternating current on thecar energizing one of said conductors, an electro-responsive controldevice connected with the other of said conductors in series andnormally energized by current induced therein from the energizedconductor and a track element including a magnetic core for at timesvarying the excitation of the other conductor for producing a reductionin the energizing current normally supplied to said control device.

18. A car element comprising, yoke means forming two magnetic circuits,means for producing an alternating magneto motive force in the circuits,and a winding magnetically associated with each of said circuits andconnected in series so that the voltages induced by said magneto motiveforce will be in phase opposition.

19. In a train controlling system, a primary coil on the vehiclecontinuously energized by alternating current, a closed circuit on thevehicle including` secondary coils of unequal-voltages and connected inopposition, a relay on the vehicle normally energized by the diierencebetween the voltages; an armature on the roadway adapted to form a pathof low reluctance for the flux of the primary vehicle coil as thevehicle moves past said armature, and means to control the magneticcharacteristics of the armature, in accordance with different trackconditions.

20. In a train controlling system, a primary coil on the vehiclecontinuously energized by alternating current, secondary coils on thevehicle connected Vin opposition in a closed electric circuit, relaymeans on the vehicleadapted to be operated by the difference between thevoltages of said secondary coils, a brake control magnet on the vehicle;an armature on the roadway adapted to form a path of low reluctance forthe flux of the primary vehicle coil as the vehicle moves past saidarmature, and means for varying the Voltage in the secondary vehiclecoils in acthe armatures in accordance with different track` conditions.

22. In a train controllingsystem, a primary coil on the vehiclecontinuously energized, secondary coils on the vehicle connected inopposition, relay means on the vehicle energized in accordance with thedifferential current in said seconda-ry coils; armatures on the roadwayadapted to form a path of low reluctance for the magneticv ilux ofthevehicle coils each time the vehicle moves past one of said armatures,and coil means on `the armatures adapted to control the iiux through thearmatures, in accordance' with different track conditions.

23. In a train controlling system, a primary coil on the vehiclecontinuously energized; secondary coils on the vehicle associated withsaid primary coil and connected in opposition; relay means on thevehicle normally energized by the currents in said secondary coils; aplurality of insulated block sections constituting a track for saidvehicle; an armature associated with each block section over which saidvehicle coils may pass and forming a path of low reluctance for themagnetic flux of said vehicle coil; and magnetic means .associated witheach armatureY adapted to control its magnetic characteristics.

24. Influence communicating means for automatic train control systemscomprising, a carcarried ycore having a primary coil thereon normallyenergized byv alternating current, a secondary coil on `said coredisposed adjacent said coil, a secondary bucking coil on said corelocated a considerable distance from said primary coil and connected inseries with said secondary coil, and traffic controlled trackway meansfor reducing the reluctance of the magnetic circuit including saidprimary coil and said bucking secondary coil under predetermined trafficconditions ahead. i

25. Inuence communicating means for automatic traincontrol systemscomprising, a carcarried core having a primary and a secondary coilthereon, said primary coil being energized by alternating current, acontrol relay having a front contact, an energized circuit for saidcontrol relay including the winding and front contact of said relay andsaid secondary coil, and means partly on the vehicle and partlyalong thetrackway for inducing a voltage in said circuit.

26. Influence communicating means for automatic train control systemscomprising, car-carried apparatus including a control relay, a core, aprimary and a secondary coil on the core,a bucking secondary coil on thecore and connected in series with said secondary coil, means forcontinuously energizing said primary coil by alternating current wherebya voltage is induced in said secondary coil predominating over theopposed voltage induced in said secondary bucking coil, thus producing acurrent for maintaining said relay energized, and trackway means forde-energizing said relay by increasing the voltage in` said secondarybucking coil without materially increasing the voltage in said secondarycoil, whereby a systeml is formed in which a failure of energizingcurrent for said primary coil causes de-energization of said relay.

27. Influence communicating means for automatic train control' systemscomprising, a carcarried core, having a primary coil thereon normallyenergized by alternating current derived from 'a car-carried source, acontrol relay, another coil on said core, a circuit including thewinding of said control relay and said other coil, means for inducing avoltage in said circuit to maintain said relay energized, and traiccontrolled trackway means for inducing a voltage in said other coil tode-energize said relay.

28. Influence communicating means for automatic train control systemscomprising, a carcarried core having a primary coil thereon normallyVenergized by alternating current, a secondary coil on said core disposedadjacent said coil, a secondary bucking coil on said core located aconsiderable distance from said primary coil and connected in serieswith said secondary coil, and tra-nic controlled trackway means fordiverting flux passing through said primary and secondary coils fromleakage paths through said secondary bucking coil.

29. Car-carried apparatus for automatic train control systems of theintermittent inductive type, comprising a primary coil, two secondarycoils connected in series, a source of alternating current forenergizing said primary coil,V train control means having two windingsone of which is connected in series with said secondary coils and acontact closed when said train control device is energized, saidsecondary coils being located with respect to said primary coil to causemore alternating flux to link one Secondary coil than the other and tocause the flux to induce opposing voltages in the circuit of saidsecondary coils thereby inducing sufficient current in said one windingof said train control device to maintain it energized, trackway meansactive under adverse tralicV conditions ahead to cause ux linking saidone secondary coil to be diverted to link the other secondary coil andcause de-energization of said train control device, and `other trackwaymeans effective under clear trafiic conditions ahead to produce a ovv ofcurrent in the other winding of said train control means for restoringit to normal.

30. Car-carried apparatus for automatic train control systems Vof theintermittent inductive type,

comprising a primary coil, two secondary coils connected in series, asource of alternating current for energizing said primary coil, traincontrol means having two windings one of which is connected in serieswith said secondary coils and a contact closed when said train controlmeans is energized, said secondary coils being located with respect tosaid' primary coil to cause more alternating flux to link one secondarycoil than the other and to cause the flux to induce opposing voltages inthe circuit of said secondary coils thereby inducing suiiicient currentin said one winding of said train control means to maintain itenergized, trackway means comprising an inert magnetic body when in itsactive condition and active under adverse traic conditions ahead tocause ux linking said one secondary coil to be diverted to link theother secondary coil and cause de-energization of said train controlmeans, and other trackway means effective under clear traffic conditionsahead' to produce a flow of current in the other winding of said traincontrol means for restoring it to normal.

31. A cab carried source of altern-ating current, a differentialinductor designed to be continuously energized by said current andprovided with two magnetic paths, a rst path of normally lesser and asecond path of normally greater reluctance, a tr-ain stop means normallysustained in a predetermined position by flux in the first path, and atrack element designed to reduce the reluctance of the second path belowthat of the rst path when desired and thus operate the train stop means.

32. In an intermittent inductive train control system, the combinationwith a car-carried receiver having a magnetic structure with two partialmagnetic paths, each path including a separate air gap, said paths beingrespectively of greater and lesser reluctance, a car-carried source ofalternating current, a winding on said receiver constantly energizedfrom said source and supplying alternating flux to both of said magneticpaths, a secondary coil on the receiver linked by the flux in themagnetic path of lesser reluctance, an electro-responsive device on thecar electrically connected to said secondary coil and normally energizedby the current induced therein by the alternating current in saidconstantly energized Winding, a track inductor acting upon movement ofthe receiver thereby to decrease the reluctance of said magnetic path ofthe receiver having the greater reluctance and thereby reducing thecurrent in said secondary coil and causing operation of saidelectro-responsive device, a winding on said track inductor, and meansfor at times connecting said track inductor winding in a closed circuit.

33. In an intermittent inductive tr-ain control system, the combinationwith a car-carried receiver having two partial magnetic paths ofdiiferent magnetic reluctance, each of said magnetic paths having an airgap therein, a source of alternating current on the car, a Winding onthe receiver constantly connected to said source for exciting both ofsaid magnetic paths with alternating uX, secondary coils on the receiverrespectively linked by the ux in said magnetic paths and each having avoltage induced therein by the constantly energized Winding dependentupon the reluctance of its corresponding magnetic path,electro-responsive means on the car responding to the diierence in thevoltages induced in said secondary coils, a track inductor acting uponmovement of the receiver thereby to reduce the reluctance of themagnetic path of the receiver having the greater reluctance and therebycausing operation of said electro-responsive means, a winding on saidtrack inductor, and means for at times connecting said winding of theinductor in a normally closed circuit.

34. A train control system comprising the following combination; atrain-carried source of alternating current and associatedsignal-receiving circuit, a train-carried unit for transmitting currentto and receiving current from the Wayside comprising inductor coils and'means whereby the source impresses two opposing E. M. F.s upon thereceiving circuit for the purpose of increasing the sensitivity of thereceiving circuit to the influence of a wayside circuit, together with aw-ayside system which includes coils functioning simultaneously toreceive current from and transmit current to the train, and relay signalcontrol means.

35. In combination, vehicle carried mechanism, a vehicle carriedinductor means including an energizing inductor associated with andadapted to be influenced for tripping the said vehicle carriedmechanism, a second vehicle carried inductor means including an energyreceiving inductor associated with and adapted to be influenced forresetting the vehicle carried mechanism and a roadside inductorium meansoperable in response to a given roadside condition for influencing thefirst mentioned inductor means to produce the tripping action andoperable in response to another roadside condition for influencing thesecond vehicle carried inductor means to produce the resetting actionwhen the vehicle carried mechanism has been tripped and beinginoperative under such last mentioned condition for producing any changein said vehicle carried mechanism when the said vehicle carriedmechanism has not been tripped.

36. In combination, vehicle carried mechanism, a vehicle carriedinductor means including an energizing inductor associated with andadapted to be influenced for tripping the said vehicle carriedmechanism, a second vehicle carried inductor means including an energyreceiving inductor associated with and adapted to be iniiuenced forresetting the vehicle carried mechanism and roadside inductorium meansoperable in response to a given roadside condition for influencing therst mentioned inductor means to produce the tripping action and operablein response to another roadside condition for inuencing the secondvehicle carried inductor means to produce the resetting action when thevehicle carried mechanism has been tripped and being inoperative undersuch last mentioned condition for producing any change in said vehiclecarried mechanism when the said vehicle carried mechanism has not beentripped.

37. In a train control system, in combination, a signal circuit, acar-carried source of A. C., a car-carried receiver, a primary windingon the receiver energized from said A. C. source, a secondary winding onthe receiver inductively related to the primary and arranged to controlthe signal circuit, the primary winding being arranged to send fluxthrough the secondary winding in a manner to produce opposing E. M. F.sin the secondary winding, and a wayside inductor to cooperate with thereceiver.

38. In a train control system, in combination, a signal circuit. acar-carried source of A. C.,

a car-carried receiver including a primary winding energized from saidA. C'. source, and a secondary winding included in a circuit andinductively related to the primary winding and controlling the signalcircuit, the primary winding being arranged to produce twoopposingcurrent producing inuences upon the circuit of the secondary winding,and a wayside element for inuencing the action between the primary andsecondary windings.

39. In a train control system, in combination, a car-carried source ofA. C., a car-carried receiver including a primary winding and aninductively related secondary winding, the primary winding beingconnected to the A. C. source, the secondary winding being included in acontrolling circuit, the primary winding being arranged for producingtwo A. C. uxes one only of which may dominate to produce an A.

20 C. current in the controlling circuit, and a Wayside inductor forVarying the inductive relationship between the primary and secondarywindings.

40. In combination, vehicle carried mechanism comprising a controlrelay, a transformer including primary and secondary coils associatedtherewith, the said primary coil being adapted to be influenced forproducing a predetermined operation of said relay, a resetting circuitfor said relay, an indication receiver for operating the resettingcircuit and a Vehicle inductor adapted to Vbe influenced for operatingthe indication receiver; and roadside mechanism comprising roadsideinductor means operable in response to a given roadside condition forinluencing said primary coil and operable in response to anotherroadside .condition for being energized for inuencing the said vehiclecarried inductor.

NED C. L. BROWN.

